UCMs (Universal Communication Modules) refer to a range of products that allow Comfort to communicate to various systems (eg PCs, LAN, 3rd party products)
UCMs consist of a baseboard with a microcontroller and firmware, and a plug in module containing the interface which fits on top.

UCMs belong to one of 2 groups;

Comfort Protocol UCMs

External Protocol UCMs

Comfort Protocol UCMs communicate according to theComfort Protocol
These include;

UCM/ETH03 with Infrared Learner and RJ45 connector for connection to Local Area Network

The above 2 UCMs have the same firmware, and the only difference is the plug-in interface submodule. The plug in interface submodules can be removed and exchanged depending on the required USB or ethernet interface.

For convenience of stocking and ordering, the above UCMs can be ordered separately as UCM06 baseboard without interface and USB01 (USB submodule) or ETH03 (Ethernet submodule).

UCM/ETH03 and UCM/USB can both be used to program Comfort using the free Comfigurator Software and they can also be used with other software applications that communicate using the Comfort Protocol. For example, the Comfort iOS and android apps require the UCM/ETH03.

Other independently developed software applications like ComfortClient require the UCM/ETH03 to talk to Comfort

UCM/ETH03 and UCM/USB can also be used to Upgrading firmware on Comfort, other UCMs, and KP06 and KT03 keypads.

External Protocol UCMs are Application-specific UCMs which interface to specific third party systems and do not use the Comfort Protocol. It is not possible to program Comfort using these UCMs. These include

UCM/CBUS for CBUS by Schneider

UCM/KNX for KNX products

UCM/Zwave for Z-Wave wireless products

UCM/Velbus for Velbus by Velleman

UCM/GSM for GSM/SMS

UCM/Heatmiser for Heatmiser thermostats

UCM/Dupline for SmartHouse/Dupline

UCM/Universal for most other 3rd party systems which do not have a dedicated UCM Interface. The Universal UCM requires a AUX485, ETH03 or RS232 submodule depending on the type of interface of the other system.

UCM/Ulti for Clipsal Ulti RF switches

These UCMs consist of a baseboard and plug in module which has the specific interface.
The UCM baseboard is NOT the same as the UCM06 (used in UCM/ETH and UCM/USB). The firmware on the UCM baseboard is specific for each type of interface submodule. Firmware for one type of UCM cannot be upgraded to a different type.

The UCM/USB with USB Interface is shown here
The 1st photo below shows the new version of the UCM/USB with SW7 shunts replaced by DIP switches. The shunts may fall out and may lose contact with the headers after a long time.

The older version of the UCM/USB with Shunts instead of DIP switch for SW7 is shown below. However the function is the same. The UCM ID can be set by using the COPY Button instead of the shunts, see http://www.comfortforums.com/forum4/3418.html

The older UCM/Eth02 (replaced by UCM/ETH03) is shown here. The outline size of UCM/ETH03 and UCM/ETH02 are the same despite the apparent difference in the scaling of the images
The most visible difference is the the ETH03 submodule is larger than the ETH02 submodule. an ETH03 submodule can be purchased to replace the ETH02 module on the UCM baseboard (UCM06)

The UCM/ETH01 is shown below

UCM/ETH01 and UCM/ETH02 are no longer in production

UCM/ETH03 can be used by the Comfort iOS and Android apps as well as to program Comfort via ethernet. It can also be used by 3rd party software like ComfortClient which communicate according to the Comfort Protocol

UCM/ETH03 can be used for remote programming of Comfort via the Internet (with suitable port forwarding)

The old version UCM01, now no longer in production is shown below. These cannot be used to upgrade Comfort II firmware. They have a label marked with firmware up to UCM 5.92
Another old UCM with RS232 interface is the UCM05 which is also obsolete